On Sat, 05 Apr 2008 17:07:40 GMT, Jim Rojas
wrote:

Yes, I have done that. I took it apart and ran water through the heat
exchanger. The engine stays cool. I also ran water downwards to the
intake, and it flows. If I use the muffs and try to pump water up, there
is no continuous flow at all.

It sounds like you have an obstruction in your leg. Have a qualified
Mercruiser guy take a look at it, might be a simple fix if it was
assembled incorrectly after the impeller change. There is an insert
that has to be positioned properly as you re-attach the leg.